Prior work in this laboratory has produced evidence that immunoadsorbent columns coated with a protein antigen and placed in an extracorporeal thoracic duct circulation of an animal produces selective immunosuppression to that antigen alone, leaving the remainder of the animal's immune mechanism intact. Utilizing this mechanism, the following objectives are being pursued: 1. To prevent the development or reverse the effect of experimental allergic encephalomyelitis in sheep by the use of immunoadsorbent columns coated with myelin basic protein placed in an extracorporeal thoracic duct circulation. 2. To prevent the rejection of experimental renal allografts by the use of columns coated with appropriate histocompatibility antigen-containing extracts placed in an extracorporeal thoracic duct circulation. 3. To prevent the rejection of experimental renal xenografts by the use of columns coated with appropriate histocompatibility antigen-containing extracts placed in an extracorporeal thoracic duct circulation. 4. To investigate certain basic characteristics of the removal of specific immunocompetent cells by antigen-coated immunoadsorbent columns. If the above studies are successful to any substantial degree, then the induction of specific tolerance utilizing antigen-coated columns will be established as a practical possibility in the fields of transplantation and autoimmune disease. The next step would then logically be the application of this method to patients with autoimmune disease or in need of organ transplants.